Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen
For vehicles that have refrigerant lines with no threads for connecting the A/C Adapter Set -V.A.G 1785-. Use, for example, an air blow gun with a rubber mouth piece or an adapter from the Refrigerant Circuits Adapter Set 1 for blowing through the individual components. When using an air blow gun with a rubber mouthpiece, take special care not to damage the connections (bending or scratching).
Evaporator is to be blown out via the connection for low pressure line (large diameter) with the expansion valve or restrictor removed.
Always blow through components in direction opposite to refrigerant flow (or flush with refrigerant R1234yf)
Check the expansion valve and replace if dirty or corroded.
Locate any components on which dark, sticky deposits cannot be removed with compressed air and either flush them using refrigerant R1234yf or replace them.
Thin, light gray deposits on the inside (of pipes) do not impair the function of the components.
After blowing through the receiver/dryer (dryer cartridge) or reservoir and restrictor. Replace the dryer cartridge on condensers that have one installed in the integrated receiver/dryer.
Condensers with an integrated receiver/dryer or dryer cartridge that cannot be replaced separately or are not available as a replacement part must be replaced after flushing the refrigerant circuit. Refer to the Parts Information and Refrigerant Circuit .
Depending on the version, there may be an additional filter element on receiver/dryers where the dryer cartridge can be replaced separately. This filter element must be replaced with the dryer cartridge if necessary.
After blowing through the refrigerant circuit:
-- Replace these vehicle-specific components (restrictor and reservoir, expansion valve and receiver/dryer or dryer cartridge). Refer to Refrigerant Circuit and the Parts Information.
-- Depending on the concern replace the A/C compressor (refer to Refrigerant Circuit and the Parts Information ) or let the remaining refrigerant oil flow out of the removed A/C compressor (refer to COMPONENTS, REPLACING ) and re-fill the prescribed quantity of fresh refrigerant oil. Refer to Technical Data and APPROVED REFRIGERANT OILS AND REFRIGERANT OIL CAPACITIES .
There is a specific prescribed amount of refrigerant oil in the replacement A/C compressor. On vehicles with two evaporators if necessary install an additional certain amount of refrigerant oil in the circuit. Refer to Technical Data and Refrigerant Circuit .
If the A/C compressor will not be replaced, replace the refrigerant oil quantity in the A/C compressor to the specified capacity (pour out the refrigerant oil and refill the prescribed quantity into the A/C compressor or refrigerant circuit). Refer to COMPONENTS, REPLACING , APPROVED REFRIGERANT OILS AND REFRIGERANT OIL CAPACITIES and Refrigerant Circuit .
-- Completely reassemble the refrigerant circuit again. Refer to Refrigerant Circuit .
-- Evacuate and fill the refrigerant circuit according to the procedure. Refer to REFRIGERANT CIRCUIT, EVACUATING and REFRIGERANT CIRCUIT, CHARGING .
-- Start up the A/C system according to specification. Refer to Refrigerant Circuit and A/C SYSTEM, OPERATING AFTER CHARGING .